利用环境同位素及水化学分析方法研究发现,岱海除了接受降水的直接补给之外,还接受泉水的补给.岱海周边泉水与井水的δD、δ18O值比当地降水明显贫化,泉水、井水显然不是来自于当地降水的补给;通过对岱海周边包气带土壤水中的氢氧稳定同位素分析发现,土壤水中的δD、δ18O值比当地降水值贫化,在地表埋深1 m附近,土壤中的盐分发生了累积,土壤水中的含盐量明显超过了土壤受蒸发所引起的增加量.研究表明岱海周边地区的大气降水不能入渗补给到潜水中,补给岱海的泉水不是来自于当地降水,而是具有同位素贫化特征的外源水.由此推断,在地层中可能存在一种地下水深循环的跨流域补给方式.在内蒙古高原地区,深循环地下水是维系湖泊不可或缺的补给源.%In search for the origin of groundwater,a detailed investigation of the stable isotopes of oxygen and hydrogen in the lake water,springs,well water,dam water,as well as soil water extracted from the four soil profiles in the Lake Daihai region,were carried out.Isotopic and hydro-chemical analysis found that apart from the direct precipitation supply,Lake Daihai is also recharged by the spring water.The mean isotopic compositions of local precipitation are much higher than those of spring water and well water collected from the surrounding areas,which means that the spring water is not supplied by the local precipitation.According to the isotopic analysis of soil water extracted from the four soil profiles around Lake Daihai region,the δD,δ18O values are significantly lower than those of the local precipitation.Furthermore,the TDS reach their peak values about 1 m beneath the earth surface,higher than the theoretical values due to evaporation.It evidenced that the local precipitation can not infiltrate into underground,in another word,the spring water of Lake Daihai is not supplemented by the local precipitation.In concluding,the results show that the main recharge source of groundwater in the Lake Daihai region is not local precipitation,but most come from a region where the precipitation is characterized by much lower δD,δ18O values.We can deduce that there is a kind of recharge ways we had not reveal before deep down in the earth's crust.In the Inner Mongolia plateau,deep-circulation groundwater from extemal drainage area is an essential source of recharge.
展开▼
